1. Field of the Invention
The field of the invention relates to apparatus for addressably controlling remote units. The preferred embodiment is an apparatus which is useful in an electric power company load management system which includes a central message generator, and a plurality of addressable load controllers which selectively connect and disconnect high power deferrable loads to and from a power source in response to transmitted messages.
2. Description of the Prior Art
The power systems of electric power companies regularly encounter periods of peak load demand. During these periods the power drain placed upon the power system is significantly higher than average. The peak load periods vary according to the time of day and the seasons of the year. It is excessively costly to maintain the supply of power during these peak load periods, but if the power demand is not met the result can be power failure or blackout.
In a load management system, the power supply and demand are monitored, and certain high power deferrable loads, such as water heaters and air conditioners, are selectively turned off to evenly distribute the power demand over time, thereby alleviating peak load periods. The result is a more efficient and less costly power system. It is also desirable for a load management system to be able to scram, or disconnect, a large number of deferrable loads in a short period of time to avoid the occurrence of a blackout.
Apparatus for addressably controlling remote units have been used in other fields, such as for telephone paging, burglar alarm systems, remote control for repeater systems, etc. However, these units operate with schemes which often require relatively long message times, or expensive receiving equipment, or a small number of addressable units. Moreover, many of these systems have a significant problem with noise interference.